Proinflammatory cytokine release was measured from peripheral blood mononuclear cells (PBMCs) isolated from six volunteers and, on admission, from 16 patients with acute pancreatitis. Tumour necrosis factor (TNF) release in patients did not differ significantly from that of volunteers, whereas both interleukin (IL) 6 and IL-8 release in patients was raised when compared with that in the volunteer group (mean(s.e.m.) IL-6 20.7(4.6) versus 9.3(1.7) ng/ml, P = 0.03; IL-8 283(40) versus 128(22) ng/ml, P = 0.04). When variation in white cell count was accounted for, IL-6 and IL-8 release but not that of TNF was significantly greater in patients with severe disease than in those with mild disease. These results point to a complex upregulation of proinflammatory cytokine release from PBMCs in patients with acute pancreatitis, components of which relate to the clinical progress of the disease.